Announcement

Collapse
No announcement yet.

How can I test non-polarized capacitor?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #21
    When I desoldered R831 and solder 60w bulb, I measured B+ filter capacitor and It was measured 120Vdc.

    So I think that there is no faulty in the HOT area. So I doubted maybe there was loose contact on the pin of IC,Beacuse This CRT TV was manufactured over 25 years,So solder joint would not as tight as twenty five years ago.

    And it seems that weight of its PCB is about 2kg,I think that Whenever I deposited this heavy PCB on the floor,this would put pressure on the pin of IC ,So there would be minor crack on its solder joint.

    I soldered all pin of IC01(LG8708-08A), IC201(GL3812),IC501(TB1231N) and Turner TU101(TUSHB-A07A) at the bottom of PCB, and It finally displayed screen!

    But there is some weird issue for this CRT TV.

    If I frequently press channel up or down button It sometimes make it mute like below video.

    https://www.dropbox.com/scl/fi/d667w...=ralpc4qj&dl=0

    And Display suddenly become distorted(concave), after switch on CRT TV in 10-20 minutes.

    https://www.dropbox.com/scl/fi/v2qdo...=3ksy8xoi&dl=0

    I doubt that there is still loose contact somewhere in the bottom of PCB..
    Last edited by chth96; 07-05-2024, 11:44 PM.

    Comment


      #22
      Originally posted by stj View Post
      maybe - try it
      One thing I would add is check the voltage on the led light side of the device to make sure that it is in the range of voltage that is needed for the device to work properly and make sure that control side of the device is within the range of the original device that is in the device now that you are working on
      9 PC LCD Monitor
      6 LCD Flat Screen TV
      30 Desk Top Switching Power Supply
      10 Battery Charger Switching Power Supply for Power Tool
      6 18v Lithium Battery Power Boards for Tool Battery Packs
      1 XBox 360 Switching Power Supply and M Board
      25 Servo Drives 220/460 3 Phase
      6 De-soldering Station Switching Power Supply 1 Power Supply
      1 Dell Mother Board
      15 Computer Power Supply
      1 HP Printer Supply & Control Board * lighting finished it *

      These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%
      1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
      2 Hem Saw Computer Stack Board
      All of these had CAPs POOF
      All of the mosfet that are taken out by bad caps

      Comment


        #23
        check the soldering on everything mounted to a heatsink,

        Comment


          #24
          Originally posted by chth96 View Post
          When I desoldered R831 and solder 60w bulb, I measured B+ filter capacitor and It was measured 120Vdc.

          So I think that there is no faulty in the HOT area. So I doubted maybe there was loose contact on the pin of IC,Beacuse This CRT TV was manufactured over 25 years,So solder joint would not as tight as twenty five years ago.

          And it seems that weight of its PCB is about 2kg,I think that Whenever I deposited this heavy PCB on the floor,this would put pressure on the pin of IC ,So there would be minor crack on its solder joint.

          I soldered all pin of IC01(LG8708-08A), IC201(GL3812),IC501(TB1231N) and Turner TU101(TUSHB-A07A) at the bottom of PCB, and It finally displayed screen!

          But there is some weird issue for this CRT TV.

          If I frequently press channel up or down button It sometimes make it mute like below video.

          https://www.dropbox.com/scl/fi/d667w...=ralpc4qj&dl=0

          And Display suddenly become distorted(concave), after switch on CRT TV in 10-20 minutes.

          https://www.dropbox.com/scl/fi/v2qdo...=3ksy8xoi&dl=0

          I doubt that there is still loose contact somewhere in the bottom of PCB..
          I would recommend that you use a magnifying glass and very carefully check each and every soldering joints for bad soldering joints because if you found some there might be others that you could not see with the naked eye I have been there and done this before trust me check them with a magnifying glass to make sure that this not an issue that still exists
          9 PC LCD Monitor
          6 LCD Flat Screen TV
          30 Desk Top Switching Power Supply
          10 Battery Charger Switching Power Supply for Power Tool
          6 18v Lithium Battery Power Boards for Tool Battery Packs
          1 XBox 360 Switching Power Supply and M Board
          25 Servo Drives 220/460 3 Phase
          6 De-soldering Station Switching Power Supply 1 Power Supply
          1 Dell Mother Board
          15 Computer Power Supply
          1 HP Printer Supply & Control Board * lighting finished it *

          These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%
          1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
          2 Hem Saw Computer Stack Board
          All of these had CAPs POOF
          All of the mosfet that are taken out by bad caps

          Comment


            #25
            Did you reinstall the original C433 (5.6µf/50vBP) capacitor? or did you use a replacement? Check connections around Q406~Q408 and the two adjustments vr400, vr401 (pincushion and horz. size circuit) it may be a dirty control or there may also be a weak elec. cap in that area as well.
            I would resolder Q408, its connections don't look good from here.
            Another electrolytic that can cause problems in these chassis is C406 (2.2µf/160v) horz. drive transformer filter cap.
            Last edited by R_J; 07-06-2024, 08:22 PM.

            Comment


              #26
              Thank very much for all of reply.
              It is not possible to purchase bi-polar capacitor which has 5.6µf/50v specification,So I still not yet replaced it.
              I noticed that There was a crack in some pins of Q408(KTD2059-Y) and IC601(it look like below screenshot).
              Click image for larger version  Name:	IMG_20240707_114609.jpg Views:	0 Size:	6.51 MB ID:	3304881
              So I soldered these pin and There was no more distorted screen and silent while pressing channel up or down button!
              But Unfortuantely,There still remains minor issues which seems to be extremely hard to repair.

              The first is not able to display flickering screen when I play retrogame in 50Hz mode.

              As this 29 inch CRT TV(CN-29H3) only supports 60Hz mode, It must display flickering screen like below video which I recorded from working 5 inch CRT TV.
              20240708_092329.mp4 (dropbox.com)

              But It(CN-29H3) displayed black strip at the top and won't display any flickering screen like below video
              20240708_092613.mp4 (dropbox.com)

              And I heard noise of Electricity spark nearby its anode suction cap and cpt board like below video.
              20240708_102545.mp4 (dropbox.com)
              Although,It is not aloud noise at all, but rather somewhat low noise.But It seem that this noise lasted 5-10 minutes after I unplugged its ac cable.

              And When I plugged its ac cable and switched on, It display somewhat blur image for 2-5 minutes ,especially it is very blur in the menu screen,I think that it is the most annoying issue.
              Besides,I think there is blur effect on the edge of letters or characters in the screen.
              But all of below screent was taken when I made use of composite cable,So I doubt that was the way it was supposed to be done

              https://www.dropbox.com/scl/fi/0re2e...=cgns0y95&dl=0

              https://www.dropbox.com/scl/fi/61q9j...=u1z3uhn3&dl=0

              https://www.dropbox.com/scl/fi/duzzi...=3hdek47p&dl=0

              https://www.dropbox.com/scl/fi/dl6h1...=mk8nfnsu&dl=0
              Last edited by chth96; 07-08-2024, 05:40 AM.

              Comment


                #27
                check the soldering on the neck board and make sure the earth wire between the tube and neck board is o.k.
                the 50/60Hz thing can probably be fixed by ajusting the vertical hold.
                not sure on that tv if it's a variable resistor or something in a service menu though.

                Comment


                  #28
                  The problem is with your source, it is likely changing the video output signal resolution and sync polarity when the game starts, this tv is not meant for that. it is not a multi standard tv

                  Comment


                    #29
                    Thank very much for all of reply.
                    It seems that the program(Isoloader 0.7 beta1 in dreamshell) don't enable real 50Hz mode.

                    By the way,I found that there is small crack on the one of GND soldering joint in the CPT board ,So I soldered it and all of other large pins on the CPT board like below picture.

                    https://www.dropbox.com/scl/fi/zp4zw...=wc083ly5&dl=0

                    When I switched on TV,I confirmed that It display screen like yesterday,But Now I heard quite loud noise from anode suction cap and cpt board like below video.I recorded below video when I closed all of window in order to reduce noise from outside.

                    https://www.dropbox.com/scl/fi/z8778...=t5vmvk79&dl=0

                    Although It was noiseless almost as soon as I unpluged ac cable,But I really dread of this loud noise may cause burnout or burst of cathode-ray tube or CPT board itself.

                    Comment


                      #30
                      Click image for larger version

Name:	crt ground strap.jpg
Views:	53
Size:	172.6 KB
ID:	3305859 Make sure the crt aguadag coating on the crt (the black coating on the outside of the crt glass) is grounded to the chassis It sounds like a ground might be missing, this is just the high voltage bleeding off it will not burn out or burst the crt.

                      Post a couple pictures of the rear of the tv so I can see the grounding on the crt and how the ground strap connects to the chassis. I tried looking up the model number you provided but it does not seem to exist
                      Last edited by R_J; 07-09-2024, 10:57 AM.

                      Comment


                        #31
                        Originally posted by R_J View Post
                        The problem is with your source, it is likely changing the video output signal resolution and sync polarity when the game starts, this tv is not meant for that. it is not a multi standard tv
                        50Hz/60Hz does not change sync polarity, he's just got the sync ajustment a bit tight so it wont lock-on.
                        only VGA connectors change sync polarity with resolution or frequency.
                        the only thing you can do on SCART is change the input from widescreen to 4:3 by changing the voltage on the mode pin.

                        Comment


                          #32
                          Originally posted by stj View Post

                          50Hz/60Hz does not change sync polarity, he's just got the sync ajustment a bit tight so it wont lock-on.
                          only VGA connectors change sync polarity with resolution or frequency.
                          the only thing you can do on SCART is change the input from widescreen to 4:3 by changing the voltage on the mode pin.
                          It looks like the sync polarity is not the issue but there is no vert hold adjustment on this chassis, I wasn't sure how he had the box connected to the tv
                          Last edited by R_J; 07-09-2024, 04:23 PM.

                          Comment


                            #33
                            it must have the ajustments in the eeprom, hopefully one of the linked manuals explains the button sequence to get into the service menu
                            some tv's even have an option to lock the frequency (region locking) or to auto-switch.

                            Comment


                              #34
                              Thank very much for all of reply.

                              I only make use of Isoloader 0.7 beta1 in dreamshell,So there is no AV convertor like SCART or VGAbox.
                              Now, I think that flickering screen is negligible matter as There is no way to display 50Hz screen correctly in this CRT TV.

                              And I found that one of GND solder pad In the CPT board have been torn out.

                              So, I scraped remained solder pad with needle to expose copper surface and soldered it to GND pin.

                              And this time,I deliberately hindered anode cable from being very close to yoke like below picture.



                              https://www.dropbox.com/scl/fi/nf89j...=kwp7a3gx&dl=0

                              https://www.dropbox.com/scl/fi/kpygfjos5nj6c0zmjzqjg/20240710_163404.jpg?rlkey=a1pdfx2nlk7vwr4vj5zvz5u0h&st=i0v7dzp3&dl=0

                              https://www.dropbox.com/scl/fi/013nycsv4uyuxup3yxzjn/20240710_163337.jpg?rlkey=0lgkfgn0mtsasskg6nijljxv7&st=tfbu3gby&dl=0

                              https://www.dropbox.com/scl/fi/qz1l92pcb2vveac77ce31/20240710_163326.jpg?rlkey=2pr4tom4sxoi7r40x0bp8cd6h&st=7bkdcc2y&dl=0




                              https://www.dropbox.com/scl/fi/3b8ir14tlw0jsrkj3w1me/20240710_163525.jpg?rlkey=vskgy1zefjf4kd5n8p9mqj1sd&st=3e5hkff3&dl=0

                              https://www.dropbox.com/scl/fi/q469a...=d8y0cvfh&dl=0

                              It seems that there is smaller noise than yesterday.

                              https://www.dropbox.com/scl/fi/59tfi...=50r20xsr&dl=0
                              Last edited by chth96; 07-10-2024, 09:55 AM.

                              Comment

                              Working...
                              X